Rishi Sunak today refused to say if a close aide being investigated over a £100 bet on the date of the general election had been told when it would happen before he placed the wager.

The Prime Minister said he was ‘disappointed with Craig Williams, who is the subject of a probe by the Gambling Commission over a punt he made on the vote being held in July. 

The Conservative candidate for Montgomeryshire and Glyndwr placed the bet in the constituency on May 19. Mr Sunak called a vote for July 4 on May 22.

The PM’s parliamentary private secretary today admitted to ‘a huge error of judgement’ amid calls for him to be thrown out by the Tories.

And Lord Cameron, the Foreign Secretary, said he had been ‘foolish’ and might have been kicked out if it was not too late to remove him from the ballot paper. 

Speaking to broadcasters at the G7 summit in Puglia, the Prime Minister said: ‘It’s very disappointing news and you will have seen Craig Williams say that it was a huge error of judgment.’

Pressed on whether Mr Williams knew the July 4 date when placing his bet, Mr Sunak said: ‘Given the nature of the inquiry, which is confidential and independent, it wouldn’t be right for me to comment while that inquiry is ongoing.’

Using confidential information in order to gain an unfair advantage when betting may constitute a criminal offence of cheating under section 42 of the Gambling Act, the Commission said yesterday. 

Lib Dem leader Sir Ed Davey told broadcasters in Kent: ‘If someone knows the outcome of something, it seems to me morally questionable for them to put a bet on it if they know the result of that outcome.’

David Cameron lashed out at ‘foolish’ Tory MP Craig Williams today as the aide to Rishi Sunak faced condemnation for placing a £100 bet on the date of the election.

The Foreign Secretary admitted it was too late to take the Conservative candidate for Montgomeryshire and Glyndwr off the ballot paper this close to the election.

Lib Dem leader Sir Ed Davey told broadcasters in Kent: ‘If someone knows the outcome of something, it seems to me morally questionable for them to put a bet on it if they know the result of that outcome.’

Mr Williams placed a £100 with Ladbrokes from within Montgomeryshire on May 19, backing a July election. 

On May 22 Mr Sunak announced July 4 would be the date of the vote, outside No10. That would have landed Mr Williams £500. Ladbrokes raised the bet with the GC, which reportedly told No10 last week.

This morning he told the BBC: ‘I clearly made a huge error of judgement that’s for sure and I apologise.’ 

The Liberal Democrats called for a Cabinet Office inquiry to look into what Mr Williams knew at the time of his bet, with the probe to be given access to any communications between Mr Sunak and his No 10 staff.

Lib Dem deputy leader Daisy Cooper said: ‘Rishi Sunak must stop being so weak and call a Cabinet Office inquiry into this latest scandal.

‘This inquiry is needed to get to the bottom of who knew what when, and uncover whether Craig Williams knew the election date at the time the bet was placed.’

Rhun ap Iorwerth, leader of Welsh party Plaid Cymru, said there were now ‘very serious questions’ surrounding Mr Williams continuing to stand in the election.

Speaking to the press following his party’s manifesto launch, he said: ‘I don’t know how quickly that investigation will be concluded, but clearly there are very, very serious questions about the propriety of him remaining as a candidate at all in this election.’

Asked about the row today, Lord Cameron told BBC Breakfast: ‘His situation, having made this clearly very foolish decision, is that he’s being investigated by the Gambling Commission, and they have considerable powers in terms of what the consequences could be, and I think we have to let that investigation take place.’

He said he was happy to have Williams run as a Tory, but added: ‘All the nominations are in, and candidates are standing, and I don’t think we can change that. 

‘In fact, it’s very important that we don’t make alterations, after these things have been set. But obviously, he’s going to be investigated, and we’ll have to face the consequences of that investigation.’